1. Field of the Invention
The instant invention relates to torpedo launching systems and more particularly to a water cylinder and a segmented flow-through piston for use in a torpedo launching system.
2. Discussion of the Prior Art
Referring to FIGS. 1 and 2, a conventional torpedo launching system is illustrated and generally indicated at 10. The torpedo launching system comprises a torpedo tube assembly generally indicated at 12, a flood and drain system generally indicated at 14, and an ejection pump apparatus generally indicated at 16. The torpedo tube assembly 12 comprises a torpedo tube 18 having a breech door 20 and a muzzle door 22. The torpedo tube 18 is connected to an impulse tank 24 via slide valves 26. The torpedo tube 18 is also connected to the flood and drain system 14 via a pipe 28. During normal operating conditions, the breech and muzzle doors 20 and 22, and the slide valves 26 are closed and the torpedo tube 18 is filled with sea water. Prior to loading a torpedo 30 into the tube 18, sea water within the tube 18 is drained by the flood and drain system 14. After loading, the torpedo tube 18 is refilled by the flood and drain system 14 with sea water.
The torpedo 30 is launched from the torpedo tube 18 by means of the ejection pump apparatus 16. The ejection pump apparatus 16 comprises a water cylinder 32 having an external sea valve 34. The ejection pump apparatus further comprises an air cylinder 36. The water cylinder 32 is connected to the impulse tank 24 by ducts 38 (See FIG. 2). A one-piece water piston generally indicated at 40 is mounted in the water cylinder 32 and an air piston 42 is mounted in the air cylinder 36. The water piston 40 has a circumferential bearing land 44 and a tapered head 46. The water piston 40 and the air piston 42 are connected by a connector rod 48 which extends between the two cylinders 32 and 36. The air cylinder 36 is connected to a high pressure impulse flask 50 which supplies high pressure air to the air cylinder 36. Prior to launching, the water cylinder 32 is charged with sea water by opening the sea valve 34. Once the water cylinder 32 is charged with sea water, the impulse flask 50 supplies high pressure air to the connecting rod side of the air piston 42, forcing the air piston 42 in the direction of arrow 52. Air flow from the impulse flask 50 is shown by arrow 54. Movement of the air piston 42 pulls water piston 40 to the discharge end of the water cylinder 32 wherein the water in the water cylinder 32 is forced into the impulse tank 24 and then into the torpedo tube 18 to force the torpedo 30 out of the tube 18. As the water piston 40 nears the end of the ejection stroke, the bearing land 44 of the water piston 40 moves past the ducts 38 allowing water on the far side of the piston 40 to flow over the tapered head portion 46 into the impulse tank 24.
While the above-described ejection pump apparatus 16 functions adequately, there are many disadvantages in its design. For example, the present piston 40 includes only a small bearing land for forming a seal with the wall of the water cylinder 32. A wider bearing land would provide a more stable piston and would form a better seal with the cylinder wall. However, a wider land area would prevent the flow-through of water at the end of the piston stroke. In addition, the present water piston 40 requires that the external sea valve 34 have a diameter which is at least as large as the water piston 40 so that the water piston 40 can be installed into the water cylinder 32 through the sea valve 34. Large diameter sea valves are costly, and therefore it can be appreciated that a smaller size sea valve would be advantageous.